Application of lithium-ion battery energy storage technology

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(From Ofweek)

 

Lithium-ion battery energy storage technology mainly refers to the storage of electric energy. The stored energy can be used as emergency energy, energy storage when the grid load is low, and output energy when the grid load is high, for peak shaving and valley filling, and to reduce grid fluctuations.

Lithium-ion batteries refer to accumulators made of lithium-containing compounds, which mainly rely on lithium ions to move between the positive and negative electrodes to work. In addition to being used as a power lithium battery, lithium-ion batteries can also be used as energy storage batteries. Due to the high safety of lithium-ion batteries, most energy storage power stations choose lithium-ion ferrous phosphate batteries as energy storage batteries.

Lithium-ion batteries are currently the most common energy storage technology on the market, and are widely used in various personal electronic products, mobile devices and even vehicle batteries for electric vehicles. Lithium batteries are usually referred to as lithium-ion batteries, which are generally divided into energy storage lithium batteries and power lithium batteries according to their uses. Lithium batteries for energy storage are used in photovoltaics or UPS. The internal resistance is relatively large, charging and discharging speed is slow, generally 0.5-1C. Power batteries are generally used in electric vehicles. The internal resistance is small, and the charging and discharging speed is fast, generally reaching 3- 5C, the price is about 1.5 times more expensive than energy storage batteries.

Lithium-ion batteries rely primarily on the movement of lithium ions between the positive and negative electrodes to function. In the process of charging and discharging, there are only lithium ions, and there is no metal lithium. Compared with other batteries, the advantages of lithium batteries are: high energy density, long cycle life, low self-discharge rate, high energy conversion rate, fast charge and discharge, etc.

However, lithium-ion battery energy storage power stations are generally used in new energy power stations, and are relatively less used in traditional power stations. Due to the unstable voltage and the uncertain timing of wind and solar power generation, it is more conducive to grid operation to use energy storage power stations as power relays.

The currently popular lithium titanate material is also worthy of attention. It can replace graphite as an anode material. Although the energy density is not high, lithium titanate allow the battery to achieve high-rate charge and discharge, and has excellent safety performance and long cycle life.

It is understood that the application scenarios of lithium batteries on the power supply side, user side, and grid side of energy storage are as follows: energy storage applications on the power generation side include photovoltaic storage power stations, wind storage power stations, and AGC frequency modulation power stations; Storage and charging stations, home energy storage, backup power, etc., scenarios such as grid energy storage, substation energy storage, virtual power plants, peak shaving/frequency modulation, etc.

So far, for different fields and different needs, people have proposed and developed a variety of energy storage technologies to meet the application. Lithium-ion battery energy storage is currently the most feasible technical route.

From the perspective of the economics of energy storage technology, lithium-ion batteries have strong competitiveness, while sodium-sulfur batteries and vanadium redox flow batteries have not yet formed industrialization, supply channels are limited, and the cost is high. From the perspective of operation and maintenance costs, sodium-sulfur batteries need continuous heating, vanadium redox flow batteries need pumps for fluid control, which increases operating costs, while lithium-ion batteries require almost no maintenance.

According to public data, there are already 20 lithium-ion battery energy storage projects in China, with a total installed capacity of 39.575MW. Energy storage is one of the important means to solve the intermittent volatility of new energy wind power and photovoltaics, and realize the function of peak shaving and flat valley. Energy storage lithium-ion batteries are also gradually being valued as an emerging application scenario.

Lithium-ion battery is a very important energy storage technology, widely used in portable electronic devices and new energy vehicles, the cost of global energy storage batteries is continuing to decline. However, future energy storage methods will shift from lithium-ion batteries to more abundant and innovative solutions.